Composite triple beat (CTB) impairments, one of the major impairments in cable television, are known to be caused by the non-linearity of amplifiers in the cable distribution network. Composite triple beats (CTB) manifest themselves as horizontal streaking patterns on the picture and are extremely irritating to viewers, to the extent that the threshold of perceptibility is found to be significantly higher than other noise levels (currently the CTB is noticeable at readings about 57 dB in terms of carrier-to-CTB noise ratio (CNR)).
When a number of different channels are transmitted simultaneously through the same cable network, these signals must be amplified at various locations along the network and since the amplifiers are not ideally linear, third-order distortion inevitably occurs forming what is known as third-order intermodulation beat products having frequencies that are combinations of the carrier frequencies of any two or three of the transmitted channels. A composite triple beat (CTB) is a cluster of such spurious signals having similar frequencies.
There is no known system for reducing or substantially eliminating the visual effect of CTB.